The devices and methods provided herein relate to microfluidic design and control so as to precisely, accurately and reliably tune dynamic components of a fluid. In this manner, an array of microfluidic gradients can be produced simultaneously without any need for fluid valves or other complicated flow control elements.
The ability to precisely and reliably deliver materials has a number of important applications, ranging from surface processing, chemical or biological reactions, assays, materials and biological research, clinical diagnostics, and other related applications known by those skilled in the art. Furthermore, of interest is the ability to provide gradients of a parameter, such as a concentration gradient, including for biological applications where chemical gradients rather than simply the presence or absence of a chemical is important. Much research and development has been centered on platforms and methods for generating gradients, including U.S. Pat. Nos. 7,470,403; 7,314,070; 8,377,685; 7,837,379; 7,112,444; 7,947,491; and 8,021,480, for example. Although that work offers unique profile intensities, unique profile shapes, or tunability, there is a need for a platform that allows for all three of these crucial criteria to be probed and/or manipulated. Presented herein are methods and devices that provide the ability to simultaneously and in a parallel manner, generate uniquely shaped gradients with controlled magnitudes, wherein on-the-run tuning permits the selection of desired gradient shapes and magnitudes. Such methods and devices represent a fundamental improvement in the art and may be employed in any number of wide-ranging applications.